Cool game... took me back to the old 8bit platformers that got me into gaming in the first place. It's obvious that you took the time to do this well, and I think you nailed it. Anyone who enjoys platform games will find this game immensely enjoyable. The fact that you took such a moody and cool setting to base the game in only enhances what would be a fine game in any thematic setting. You could've done something boring and gotten away with it, but you didn't, and that's excellent.
I honestly can't point out any room for great improvements, but I'm sure if you keep putting this kind of effort into all your creations, that they will only get better and better.